A Virtual-SIM (VSIM) is subscriber identity module (SIM) software that acts as a SIM interface with a mobile communication device. A physical SIM corresponding to the VSIM may be available at remote server. When the physical SIM is necessary for authentication purpose, the VSIM accesses a remote SIM server using a secure Internet protocol (IP) tunnel. To enable the VSIM to establish the secure IP tunnel to the remote SIM server the mobile communication device may utilize a software SIM (soft-SIM). The soft-SIM may be preloaded or downloaded to the secure file system of the mobile communication device. The soft-SIM may remain preloaded in mobile communication device and may be used by the mobile communication device to only access the remote SIM server using remote sim access protocol (RSAP) over the secure IP tunnel.
A typical use of a VSIM may be when a mobile communication device roams. A user may roam to a foreign country, use international roaming to configure a VSIM in a SIM slot and perform data services at low cost in the foreign country. The user's network operator or a third party may act as a Mobile Virtual Network Operator (MVNO) in the foreign countries and offer roaming data services at discount. The user's network operator may provide a VSIM application that configures the VSIM and soft-SIM and deactivates the physical SIM.
A conventional dual-SIM dual-standby (DSDS) or multi-SIM multi-standby (MSMS) mobile communication device utilizing a VSIM may perform authentication procedures for circuit switched (CS) and packet switched (PS) activation, for example, registration procedures such as location area update (LAU), routing area update (RAU), tracking area update (TAU), and attach procedures. To activate the VSIM PS connection, the mobile communication device may tune away from VSIM network and connect to the soft-SIM network using the soft-SIM subscription. The soft-SIM subscription may acquire an Authentication Response and corresponding keys from the remote server. During this time, the VSIM subscription triggered connection may remain disconnected. The disconnection may be in the order of few seconds and VSIM PS connection may subsequently be re-established. However, issues may arise when activating the VSIM CS connection.
When activating the VSIM CS connection, long tune away may lead to delay in establishing CS calls. Also, long tune away may result in abnormal CS call release or complete service denial due to the VSIM network interpreting the time to receive a response to authentication as abnormal. Further, if the mobile communication device is in mobility chances of missing handover messages and/or measurements increases. Also, if the soft-SIM subscription is in mobility a long tune away duration may be necessary to accommodate cell reselection, system information block (SIB) reads, acquisitions, etc.